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New reference speakers - "Delusion P24"

Finished in MARCH 2009 - read on the bottom of the page.

P24 Anniversary Edition

(18th anniversary of my speakerbuilding)



They are that good.  Sabas I mean.
The only way out of the ballpark hole is to go "expenceive exotica", because there are no other areas for me to discover. I have tried commercial standard drivers, vintage drivers, and I pretty much know them all.

I generally refused to use $$$ drivers, hand-made in Japan from rice paper. As much as I refuse to start saving for Ongaku and the like. Let me admire those from a safe distance and walk firmly on earth.

Having said all that I broke this rule and I treated myself to a very special driver, hand made in Serbia by Mr. Aleksandar Radisavljevic, a very nice man and talented ribbonbuilder.
I selected this ribbon solely on the basis of good opinion on internet.
I made an assumption, that if someone is from Serbia (I mean small country not usually associated with High End or metalwork), he must be damn good to make such success in this americanized world.

So the plan is this: to make the most  crazy marriage of 21st century hi-tech ribbon to the vintage Altec Lansing from the 60's.

Russian tubes, Ukrainian amps, German CD, American drivers and Serbian ribbons. And a Polish maker.  Enter The P24...


The Target: uncompromised, full scale, full bandwidth speakers for the tube amplifier

The Plan:
- three way
- 96 dB/m/W minimum
- open baffle
- musical
- transparent
- uncolored
- fast transient
- time coherent
- biwired
- easy to drive by OTL amps

The solution:



Mr. Aleksandar Radisavljevic was totally deaf to my begging for special discount. Despite my price pressure he basically told me to go and get stuffed (in a very polite and friendly way). That caused my curiosity to rise. How dare he to treat Doctor Lampizator, the self proclaimed Prometheus like this? !!!
Gee, these drivers simply MUST be good. Or rather "they better be good".
I ordered the speakers for the retail price and I mumbled something like a promise of my vengeance in the www review. Wait my man, I will mop the floor with these drivers if they are bad.
A week later, upon close inspection when they arrived - my eye pupils went wide open. Full F1,4 iris. What I was holding did not even resemble the Ravens. This is some serious shit - I thought.

I could not possibly wait to try them with the Altecs a month later or so when the Biflex will arrive, so I immediately hooked them to my Saba Greencone P12 setup in place of the Saba10 tweeters. See photo below.
I made a quick XO consisting of a CLC filter third order - 4uF / 0,6 mH / 4uF (caps are PIO)

I sat down in my chair and with shaking hands I pressed PLAY.
A biig smile, and I was taken to heaven (a sinner or not - I went straight there through VIP gates).

Oh Dear Lord do they blend seamlessly! Total magic and match made in heaven. The experimental XO without any fine tuning sounds like there is nothing more to do. A month later i shorted the second cap, leaving only the first series 4uF)  The top end extension, the purity, the tonality, the zzing and the zzang, all is there !

Lack of any distortion, any coloration, any sizzling, spitting, sibilance - absolutely none of the above. I must admit I did not expect them to be that good. Also the critical SPL is right there with the Greencone around 98 dB.
The amount of detail information available from my Lampizator CD players is scary on the RAALs.
I do not know how a standard op-amped CD with transistor amplifier would sound on these, because the electron microscope which the RAALs are would mercilessly show the dirt in the op-amped system. These drivers do not "make the system sound good", they make a good system sound true. But on my system this is the best I can imagine. They make music, they reveal detail, they do the 3D, the goosebumps, etc. The whole package.
And by the way - the foam waveguides do work ! I love it! Just what the Raven was missing.

After a month -after I slightly touched the XO, I just listen, listen listen. I can not name a single fault about the sound or construction of the RAAL, except that I completely don't understand the wire terminals they used. (After a year I confirm everything)  But that is a minor issue compared to the fact that one of the best tweeters ever made can be had for an acceptable sum of around 1000 Euro a pair including shipping by DHL and all EU duties and VAT. Cheap ??? Surely not. But value for money - YES.

The test drive .......

Feb 29th 2008:
All of the above blah blah was written about the RAALs working with SABA mids, awaiting partnering with the Altecs as below.
I decided to keep the RAAL XO and just adjust the Altec to the RAAL's curve. I succeeded with the below XO for the Altec.
The blend is not as seamless as with the Sabas although it is absolutely good enough.
And the main thing - the phase timing - is achieved only when the front plane of the RAAL is 5 mm in front of the front plane of the Altec.
And since the Altec is rear mounted by definition (the ribs)  the RAAL must be recessed accordingly. On the same plane they measure wrong impulse response.

RAAL ribbonraal ribbon tweetr


Altec Lansing Biflex 420A  - 15 inch, single coil - dulal QTS (response limits: 28 Hz - 18k)
Paper membrane, cloth surround, alnico magnet.
It has same basket as the bass drivers with 15 inch cast frame and Alnico V magnet, but the paper cone is divided into two, connected by specially selected suspension. Or rather two outer suspensions of sticky cloth.
It is like a 20 cm midrange glued to the circular remains of a 15" bass driver. At frequencies around 100 Hz and below  the mechanical coupling allows the surrounding bass part to start moving. Above that - the surround is too heavy and behaves like a frame.

February 29 2008
Application of the biflex is a real challenge. It does not behave like a good boy, I mean like a poly seas driver so to speak.
Out of the box they sound quite spectacular, especially that they go up to 18k without sweat - that is without any filter. It is a really nice wide-range speaker. But the sound is kinda harsh and rough.

After 4 evenings with the driver I decided that I can't tolerate the metal "dustcap" dome inside. This is really like a dome tweeter, not just the dustcap.
It is supposed to extend the speaker's response from 12 K to 18 K and it does the trick very well on paper, but listening shows a metallic ringing which I hate.
So I decided that is either me or the alu dome. I took the utility knife and I cut the sucker out.
It was NOT EASY THING from mental standpoint - I was sweating like a pig.
Anyway - the driver is now MUCH cleaner sounding - like a proper vintage paper midrange for 500 dollars should be. I recommend everybody to do the same mod without slightest hesitation.

Second thing - despite amputation of the center dome - I traced on my PC the very sharp peak at 10-12 K. The driver rolls nicely at 8 K then there is plateau of silence, and a huge peak again. Something resonates in the cone. I added a 10 uF paralell cap and it just removes that peak whilst keeping the signal intact. Perfetto !!!
So the final schematics of a great sounding, totally resistorless crossover for the midrange is:
- 100uF MKP series cap, followed by 1,2 (+/- 0,2) mH series coil of low DCR below 1 Ohm and followed by parallel cap of 10 uF, volts unimportant, foil type.
I am VERY confident in this XO, please do not deviate.


Altec Lansing 408B  - 15 inch, single coil (response limits: 24 Hz - 2k)
Paper membrane, cloth surround, alnico magnet.

Tweeter: first-  C=4uF series, L=0,5 mH paralell,  Phase positive.
Mid: C=100uF series (foil) then L=1,2 mH series, then C=10uF paralell. Phase POSITIVE
Bass: L=4,7 mH iron core R<0,5 Ohm, and paralell C=80 uF. Phase negative. Your phasing may vary because my bass units are 1 m behind the mids and tweeters. If they are on same plane - the mileage may vary.
No resistors are used anywhere.

My amp which is a 2 WPC OTL is perfectly happy driving these speakers to levels at which the furniture starts moving around the room.

This is the test drive baffle. Size is 45 x 90 but I want it 15 cm higher and 5 cm wider. I also want the tweeter to be closer to the mid.  The point between the Altec and the RAAL should be on the siting position- ear level (which for my chair, my height and my ears is 1 m). Now it's the RAAL on ear level and it sounds wrong. I HATE low sounding systems. I mean music on knee height.

Altec-Raal-P24This photo is crooked, but the speaker is STRAIGHT VERTICAL. No tilt backwards.

At the time of writing this system already meets my expectation - it is my best to date and at the same time very very simple. Although not cheap anymore - you are looking at:
900 Euro for the RAAL
500 USD for the Biflex plus 250$ for shipping from USA
same about the bass.

To be continued .....

also check the P23 with  similar drivers..


Well, two years with these speakers and I still could not forget the SABA greencones. I remembered - back in the saba days - I was having real eargasms and goosebumbs and you name it. With the Altecs - I had to fake them.
So in the end  I decided to add the missing magic by going four-way and adding a midrange driver. I felt that the Altecs are too heavy footed to sing the blues.
But at the same time I felt ashamed of being so conservative and using SABA again so I picked another lovely driver - the ISOPHON OVAL.
it was known to me from PROJECT P18
I also briefly experimented with the very interesting driver from Great Plains Audio with a horn.

Great Planes Audio

GPA horn


As sexy as the hugely monstrous GPA drivers were, I was not liking their sound. I tried many variants of my XO but every time the GPA kept the sound strongly attached to them.
I admit -the GPA are not for me, I can't apply them properly with RAALs. I feel they need special full horn system a'la AVANTGARDE TRIO to sing well.
Switching to the Isophon Ovals was a big improvement - music exploded with 3-D-everywhere. And Isophon is 15 times cheaper.

It was time to build a new baffle so I designed everything from scratch.

Without my Kingston Kitchen woodworking facility, I am very limited  witrh what I can do with the router.
Anybody who tried routing MDF in the living room, will understand me. My wife - doesn't.

I made the smallest baffle which I think gives good results - I mean the baffle to be good must be bloody large so anything acceptable in the living room is already a compromise.
My baffle is 55 cm wide, 150 cm high, and 52 mm thick.
It is a sandwich of a 12 mm plywood, 20 mm MDF (back side) and front decor of 20 mm parquet floor panel.
The tweeter and the oval are squeezed  together, pretending to be a point source. They fit very nicely.

isophon and raal

I sprayed the plywood  black to make it ready for final assembly of the front decor.

I chose exotic wood parquet panels because they seemed fairly easy to apply. I was wrong. They are a nightmare to work with.

The baffle has simple foot made of scrap MDF. Just enough to hold them straight.

Sawdust and persian rugs don't go together in perfect harmony like ebony and ivory.


As you know already, for me nothing beats the bass built-in the book shelves. Simply nothing.
My long term reference were Altec Lansing Alnico 15 inch drivers.
One day they were beaten by the ultra rare and ultra expenceive Tesla ARO from Czechoslovakia. Similar to Altecs, but with lower Fs, bigger magnet, smoother cone and more pleasant bass sound.
Since it is easier to find cash on the street than it is to find a decent pair of Tesla 8 Ohm bass, I bought the 32 Ohm variant and I added a transformer. To me it works just great.

The bass from these drivers became so good, loud and deep, that the neighbours downstairs threatened me with murder.
I decided to suspend my system on a floating false floor.

I put 4 layers of cork matts and I built a wooden floor on top of it. It was really floating, not being attached, not even touching the walls. This helped the neighbour problem and my own sound is stilll very good.

Tesla (left) against the Altec (right as you might have guessed  already)

tesla aro

I have later on finished the floor's edge with a quarterround and I love the result.

Tweeter: 2,2 uF series, 0,5 mH parallel, 2nd order electrical at around 6-7K
Isophon: 100 uF series, 1 mH series first order on both ends
Altec 420 Biflex: 2 mH series, 20 uF parallel second order lowpass at around 1-2 KHz  . No Hipass.
Tesla ARO bass: 4,7mH series, 100 uF parallel, and 1:2 transformer to match 32 Ohms.  Lopass at around 250 Hz.  (amplifier load is R divided by ratio squared which is 32 / 2*2 = 8 Ohms.)
Only tesla is reversed polarity.


This system became really good by now.
Bass has improved by addition of suspended floor, and ARO from Tesla play better than my Altecs. All in all - I am even more happy with this bass solution AND I can play louder thanks to the floor thing. So I can enjoy life more, while it lasts.

The midrange is no compromise really. It is not as thin as from Saba alone, and not as thick as from Biflex alone. The Isophon is my best midrange I ever had. I love that little sucker. I am surprised how much bass it can produce on that baffle. It is really very energetic and very smooth at the same time. It's very stiff and solid basket is a class better than Sabas - which tends to ring like a bell.

The RAAL tweeter is great one, I have it for 3 years now and I wouldnt exchange it for anything else.

Here it is - my DELUSION project P24 at the end of the road.
Complicated it may be because it is a fourway. The drivers are hard to get. So I don't suggest  that anybody should copy these but maybe you can get some courage and inspiration to try your own search.

I am sticking with these.

Compared to everything that I had before, these speakers are most civillised, neutral, natural, powerful, uncolored and true. I cant detect any shortcomings.
The singers sound like living humans. Drums sound like drums. Cymballs sound like cymballs. Soundstage is wide, deep and tall. Everything I could ask for. Roger Waters barks behind my head.  Leslie Feist sings with her head in the bucket.  Ginger Baker drums like a mad shaman.  Wholle Lotta Love makes my chest hair grow.
THESE ARE MY SPEAKERS with which I am gonna grow old. I will stop at that point and there will be no more research in speaker department, at least for a while.

Lukasz in the state of  bliss....

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